The present disclosure relates generally to vehicle suspension systems and, in an embodiment described herein, more particularly provides a suspension system run height adjustment.
It is known to set a run height (generally defined as the distance between a vehicle frame and an axle or spindle center) of a suspension system by use of a leveling valve. The leveling valve maintains a desired run height by bleeding pressure from, or supplying pressure to, air springs of the suspension system to thereby raise or lower the frame as needed.
There are many circumstances, however, when it is beneficial to be able to adjust the run height to a new value, rather than to maintain a constant run height. For example, it may be desired to raise or lower a trailer bed relative to a loading dock, it may be desired to lower a trailer so that it (and/or a cargo on the trailer) will pass under a bridge, etc. In these circumstances, it has been common practice to override the leveling valve and directly bleed or supply pressure directly to the air springs as needed to adjust the run height. Unfortunately, the leveling valve is frequently not re-activated after it is overridden, which can lead to damage to the vehicle suspension.
In addition, the leveling valve is commonly mounted to the vehicle frame by the vehicle manufacturer, and not by the suspension system manufacturer, so the suspension system manufacturer cannot reliably control the placement of the leveling valve. Consequently, the leveling valve can be installed in a position which is not optimum for the suspension system.
Furthermore, the use of turntable suspensions has become more common in recent years. Unfortunately, a convenient and reliable method for adjusting the run height for a turntable suspension is not yet available.
Therefore, it may be seen that improvements are needed in the art of suspension system run height adjustment. These improvements may be useful in turntable and other types of suspension systems.